Laminates

ABSTRACT

Polysiloxane-polycarbonate block copolymers provide ductile, structural adhesive layers for bonding laminates. They are particularly useful as an adhesive and structural element in preparing polycarbonate containing composites which retain their integrity. Laminates of glass, polycarbonate, other resins separately and in various combinations and the adhesive layer provide glazing and structural units of relatively light weight and thickness which have good energy absorption, clarity, strength and integrity and are penetration resistant over a wide range of temperatures.

This is a division of application Ser. No. 586,630, filed June 13, 1975,now U.S. Pat. No. 4,027,072, which in turn is a continuation-in-part ofpatent application Ser. No. 369,663 filed June 13, 1973 and nowabandoned.

This invention relates to laminates in which the laminae are bonded byparticular polysiloxane-polycarbonate block copolymers. Moreparticularly, the invention relates to such laminates in which thespecial ductile adhesive layer contributes to the structural integrityof the laminates, providing over-all structural units of relativelylight weight and thickness which are particularly characterized byimproved penetration and spall resistance over a wide range oftemperatures.

BACKGROUND OF THE INVENTION

The use of so-called safety glazing or penetration resistant glazing forwindows, windshields and the like utilizing polycarbonate resin layersas a structural component are well known. For example, glasspolycarbonate resin laminates are described in U.S. Pat. No. 3,666,614,the glass and polycarbonate being sealed together by an ethylene-vinylacetate copolymer. U.S. Pat. No. 3,520,768 describes laminates ofrelatively thick glass having a comparatively thin polycarbonate foilinserted therebetween and adhered thereto. While such prior artlaminates of this general type are useful for certain purposes, theinterlayers or adhesives employed often have low adhesion topolycarbonate or are incompatible to the extent that the polycarbonateis attacked to the point of hazing, stress cracking and evendelamination. There is a need for materials which are characterized bysuperior penetration and spall resistance and which, at the same time,are relatively light in weight and have good clarity, strength andintegrity all over the wide range of temperatures, and it is a primaryobject of the present invention to provide such materials.

DESCRIPTION OF THE INVENTION

This invention relates to laminates which are adhered with particularpolysiloxane-polycarbonate block copolymers.

It has been found that these particular polysiloxane-polycarbonate blockcopolymers can be used in sheet form and laid up into laminates withother materials. Preferably, these other materials are selected from thegroup consisting of solid resinous materials, glass, and solidstructural materials. This solid structural material includes wood,ceramics, metals, cermets, etc.

Any of the usual polycarbonate resins can be used as laminae for thepresent invention including but not limited to those described in U.S.Pat. Nos. 3,161,615; 3,220,973; 3,312,659; 3,312,660; 3,313,777;3,666,614, among others, all of which are included herein by reference.

Any of the usual types of glass used in so-called safety applicationscan be used in conjunction with the present invention includingchemically and thermally strengthened or tempered glass as well ascommon untempered glass where indicated.

Where desirable, adhesion promoting primers can be used to promoteadhesion, such material being well known and including, among others,vinyl alkoxy silanes, amino-alkylalkoxy silanes, alkoxy silanes, silylperoxides and amino-alkoxy silanes, such materials being described inthe above U.S. Pat. No. 3,666,614 and elsewhere. A particular advantageof the present invention is that primers or protective layers are notnecessary in connection with any polycarbonate or resin used.

The solid resinous materials which may be used include ABS plasticsbased on combining acrylonitrile, butadiene and styrene; acetalhomopolymers; acetal copolymers produced by polymerization of trioxaneand ethylene oxide; acrylics; epoxy resins; nylons, those prepared froma diamine and a diacid and those prepared from an amino acid or aminoacid derivative; phenolics; polycarbonates; phenylene oxide based resinssuch as polyphenylene oxide and blends of polyphenylene oxide andstyrene resins; polyaryl ethers; polyesters, polyethylenes;polyphenylene sulfides; polypropylene; polysulfones; polyurethanes;silicones; ethylene polymers such as ethyl vinyl acetates; conductiveplastics; and ordered aromatic copolymers, etc. These solid resinousmaterials can be formed into sheets. Other materials which may beincluded within the scope of this invention are described in U.S. Pat.No. 3,662,440, which is incorporated herein by reference.

The polysiloxane-polycarbonate block copolymers can be expressed by theaverage formula: ##STR1## where n is at least 1, and preferably n is aninteger equal to from 1 to about 1000, inclusive, a is equal to from 1to about 200, inclusive, b is equal to from about 5 to about 200,inclusive, and preferably b has an average value from about 15 to about90, inclusive, while the ratio of a to b can vary from about 0.05 toabout 3, inclusive, and when b has an average value of from about 15 toabout 90, inclusive, the ratio of a to b is preferably from about 0.067to about 0.45, inclusive, and d is 1 or more, Y is ##STR2## A is amember selected from the class of hydrogen and ##STR3## R is a memberselected from the class of hydrogen, monovalent hydrocarbon radicals andhalogenated monovalent hydrocarbon radicals, R' is a member selectedfrom the class of monovalent hydrocarbon radicals, halogenatedmonovalent hydrocarbon radicals and cyanoalkyl radicals, R" is a memberselected from the class consisting of monovalent hydrocarbon radicalsand halogenated hydrocarbon radicals, and Z is a member selected fromthe class of hydrogen, lower alkyl radicals and halogen radicals andmixtures thereof.

Included within the radicals represented by R of Formula 1 are arylradicals and halogenated aryl radicals such as phenyl, chlorophenyl,xylyl, tolyl, etc.; aralkyl radicals such as phenylethyl, benzyl, etc.;aliphatic, haloaliphatic and cycloaliphatic radicals such as alkyl,alkenyl, cycloalkyl, haloalkyl including methyl, ethyl, propyl,chlorobutyl, cyclohexyl, etc.; R can be all the same radical or any twoor more of the aforementioned radicals, while R is preferably methyl, R'includes all radicals included by R above except hydrogen, where R' alsocan be all the same radical or any two or more of the aforementioned Rradicals except hydrogen, and R' is preferably methyl. R' also includes,in addition to all the radicals included by R, except hydrogen,cyanoalkyl radicals such as cyanoethyl, cyanobutyl, etc., radicals.Radicals that are included within the definition of Z of Formula 1 arehydrogen, methyl, ethyl, propyl, chloro, bromo, iodo, etc., andcombinations thereof, and Z is preferably hydrogen.

The hydrolytically stable copolymers of the present invention can befurther described as comprising recurring copolymeric units of apolydiorganosiloxane joined by substituted aryloxy-silicon linkages to apolyester of dihydric phenol and a precursor of carbonic acid, whereeach of said recurring copolymeric units comprises by average weightfrom about 10% to about 75% of said polydiorganosiloxane, and preferablyfrom about 40 to 70% by weight.

The copolymers of Formula 1 can be produced by reacting at temperaturesin the range of 0° C. to 100° C., preferably 20° C. to 50° C., and inthe presence of an acid acceptor, a mixture of a halogen chain-stoppedpolydiorganosiloxane having the formula ##STR4## and a dihydric phenolhaving the formula ##STR5## and thereafter phosgenating said reactionproduct until the resulting copolymer achieves a maximum intrinsicviscosity, where R, R', Z and b are as defined above, and X is a halogenradical, preferably chloro.

The halogen chain-stopped polydiorganosiloxanes of Formula 2 can be madeby conventional procedures such as by the controlled hydrolysis of adiorganodihalosilane, for example, dimethyldichlorosilane as taught inPatnode U.S. Pat. No. 2,381,366 and Hyde U.S. Pat. Nos. 2,629,726 and2,902,507.

Another procedure that can be employed involves equilibrating a mixtureof a diorganodichlorosilane and a cyclic polydiorganosiloxane in thepresence of a metal catalyst such as ferric chloride as shown in SauerU.S. Pat. No. 2,421,653. Although the various procedures utilized informing the halogen chain-stopped polysiloxane are not critical,generally it has been found desirable to maintain the halogen content ofthe resulting halogen chain-stopped polysiloxane in the range of about0.4 to about 35%, by weight, and preferably from about 1 to about 10% byweight of said halogen chain-stopped polysiloxane. The halogenchain-stopped polysiloxane is preferably in the form of a chlorinatedpolydimethylsiloxane.

Dihydric phenols that are included in Formula 3 are, for example,2,2-bis(4-hydroxyphenyl)-propane (bis-phenol-A);2,4'-dihydroxydiphenylmethane; bis-(2-hydroxyphenyl)-methane;bis-(4-hydroxyphenyl)-methane; 1,1-bis(4-hydroxyphenyl)-ethane;1,2-bis-(4-hydroxyphenyl)-ethane;1,1-bis-(4-hydroxy-2-chlorophenyl)-ethane;1,1-bis-(2,5-dimethyl-4-hydroxyphenyl)-ethane;1,3-bis-(3-methyl-4-hydroxyphenyl)-propane;2,2-bis-(3-isopropyl-4-hydroxyphenyl)-propane, etc. Mixtures can also beused. Others will occur to those skilled in the art.

The copolymers of the present invention essentially comprise recurringunits consisting of a polydiorganosiloxane interconnected by substitutedaryloxy-silicon linkages to a polyester of carbonic acid precursor and adihydric phenol.

Materials of the above nature are also described in U.S. Pat. No.3,189,662 included herein by reference and can be used either alone assuch or in conjunction with well known modifiers to provide particulardesired characteristics.

While the above U.S. Pat. No. 3,189,662 states that the above blockcopolymers are useful as binding materials for parts and laminates andin adhesive formulations, it was unexpectedly found that when suchmaterials are used in sheet form and laid up into laminates variouslywith other materials such as polycarbonates, other resins and glass,they provide not only excellent adhesive properties but in effect enterinto and enhance the laminate structure, providing improved strength andductility over an extremely wide range of temperatures. These physicalcharacteristics, accompanied over such wide range of temperatures bysalutary weather resistance and optical clarity, make them particularlyuseful in so-called safety glazing applications where resistance topenetration and spalling from the impact of flying objects such asbullets, rocks, missiles, and the like is desirable. It will berealized, of course, that while optical clarity and lack of color aredesirable in many cases, one or more of the laminates can be tinted orcolored as desired to provide light screening and the like. It will bealso realized that light and heat stabilizers can be employed whereindicated.

As pointed out above, it has been found that laminates using the presentblock copolymers as an adhesive and structure layer are characterized bygood properties over a wide range of temperatures, particularly ascompared to usual high penetration resistant laminates such as thoseusing polyvinyl butyral as the interlayer in glass laminates.

In preparing the present laminates, the laminae or layers are laid up asdesired and bonded as indicated using pressure or heat and pressure. Thebonding can be accomplished using presses, autoclaves, rollers, vacuumbags, vacuum rings and the like, all of which are well known to thoseskilled in the art.

There are no apparent limitations on the thickness or size of thelaminates as well as on the number of layers that may be employed inpreparing such laminates.

The polycarbonate, glass, solid resinous materials and solid structuralmaterial may be used individually or in any combination as long as thepolysiloxane-polycarbonate block copolymer adhesive layer is presentbetween one or more of these laminae. Thus, the laminate may containpolycarbonate, said block copolymer and polycarbonate; glass, said blockcopolymer and glass for example. Also, the laminate includes successivelayers of polycarbonate and said block copolymer; glass and said blockcopolymer; acrylic and said block copolymer, for example. The laminatesof this invention include combinations of polycarbonate, glass andacrylic with other materials such as: glass, said block copolymer andpolycarbonate; glass, said block copolymer, polycarbonate, said blockcopolymer, polycarbonate, said block copolymer and glass; glass, saidblock copolymer, polycarbonate, said block copolymer and polycarbonate;acrylic, said block copolymer, glass, said block copolymer,polycarbonate; polymethyl methacrylate, said block copolymer,polycarbonate, acrylic, glass, for example. Also, the laminates of thisinvention include successive layers of lamina within the combination ofmaterials such as, for example: glass, said block copolymer,polycarbonate, successive layers of said block copolymer andpolycarbonate, said block copolymer and glass; glass, said blockcopolymer, polycarbonate, successive layers of polycarbonate and saidblock copolymer.

The present laminates may be bonded to other materials which may be usedfor walls, partitions, or other solid barriers such as fiberglass,reinforced plastic board, particle boards, etc.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In order to more fully and clearly illustrate the present invention, thefollowing specific examples are presented. It is intended that theexamples be considered as illustrative rather than limiting theinvention disclosed and claimed herein. In the examples, all parts andpercentages are on a weight basis unless otherwise specified.

EXAMPLE I

There were prepared flat laminates useful for automotive windshieldsabout 2 × 3 feet having two 3/32 inch thick float glass outer layerswith a 30 mil thick interlayer film of polyvinyl butyral or the presentblock copolymer. In using the block copolymer, a primer of gamma aminopropyl triethoxy silane was used on the glass surface adjacent the blockcopolymer. The laminates were de-aired and tacked and then consolidatedin an autoclave at about 280° F. and a pressure of about 275 psi for 15minutes. Such laminates were tested for impact using a 22 lb. headformwhich is representative of the upper human torso which was impactedagainst the laminates at right angles at various velocities. The 22 lb.headform test was developed by the SAE Glazing Committee in 1962 toassess the penetration resistance and deceleration characteristics ofglazing materials. The 22 lb. headform contains a triaxial accelerometerto determine the forces on the head during impact. SAE Severity Index(SI) can be calculated meaningfully only on those specimens whichsupport the 22 lb. headform. The lower the value of SI, the less thelikelihood that dangerous concussive type injury will occur. Referenceis made to Proceedings of Fifteenth Stapp Car Crash Conference, Nov.17-19, 1971, published by the Society of Automotive Engineers, Inc., fora discussion of Severity Index (SI).

At 120° F. when the headform was impacted against a polyvinyl butyralinterlayer laminate at 19.3 mph, there was total penetration of thelaminate. SI is meaningless in this case because of penetration but wasmeasured at 98. Using a laminate having the present block copolymer asan interlayer and with a headform velocity of 18.9 mph, there was nopenetration and an SI of 98. At 73° F. a polyvinyl butyral interlayerlaminate impacted as above at 21.2 mph, experienced no penetration andan SI of 220. Using a laminate with the present block copolymerinterlayer as above and an impact velocity of 21.1 mph, the SI was 158with no penetration. At 0° F. and 20.0 mph the present material showedno penetration and an SI of 203. Using polyvinyl butyral, penetrationwas experienced at 17.2 mph. At 16.4 mph, both the polyvinyl butyral andpresent material had no penetration but the SI of the polyvinyl butyralwas 285 compared to only 228 for the present material.

At all of the above temperatures the present material has a lower SI andbetter penetration resistance. The magnitude of the differences isespecially apparent at the extremes of the temperatures at which testingtook place.

The particular block copolymer used in the above laminate was GeneralElectric LR 3320. This material has a specific gravity of 1.12, atensile strength of 2600 to 3200 psi, an elongation of 300 to 390, atear strength (Die C) of 400 lbs/in., and a brittleness temperaturebelow -76° F., and a heat deflection temperature (10 mils under 66 psiLoad) of 160° F.

The above laminates comply with American National Standards InstituteStandard USAS Z26.1--1966 item 1 relative to automotive safety glazing.

Laminates constructed using the present block copolymers also findparticular application in locomotive windshields and glazing as well astransportation glazing in general where resistance to rocks and othermissiles or flying objects is desirable. At the same time, resistance tospalling on the inboard side and protection of the occupants from flyingchards or splinters of glass is desirable. The assembled layers areheated in a vacuum bag to 250° F. and pressurized to 250 psi for 45minutes at temperature. The laminates are then cooled slowly underpressure to 120° F. and removed. A particular locomotive windshield orwindscreen consists of an outboard layer of 250 mils of primedstrengthened glass, an interlayer of 60 mils of LR 5630 block copolymerand an inboard layer of 250 mils of polycarbonate sheet with an outboardabrasion-resistant coating made by General Electric. Such a windshielddefeats penetration by heavy objects and at the same time precludesflying glass in the cab interior.

While the above inboard polycarbonate layer is quite scratch resistantin and of itself, a so-called microglass layer made by Corning can beadded. This glass layer is scratch resistant and at the same timeprecludes flying glass particles which might injure personnel. Anotherlaminate particularly useful in side windows, for example, of rapidtransit cars was prepared using vacuum rings with the immediatelypreceding heat and pressure cycle consisting of an outboard 125 milthick sheet of strengthened glass, an interlayer of 60 mils of the aboveLR 3320 block copolymer and an inside or inboard layer of polycarbonateabout 125 mils thick coated on the outer side with abrasion-resistantmaterial.

LR 5630 block copolymer has a specific gravity of 1.07, a tensilestrength of 2200 to 2500 psi, an elongation of 500-700%, a tear (Die C)of 200 lbs/in., and a brittle temperature below -76° F. and a heatdeflection temperature (66 psi) of 130° F.

The present laminates also find use in so-called security glazing, suchglazing itself being used in place of bars or metal reinforced glass orcombinations of glass and bars in penitentiaries and other similarapplications. Such laminates can, if desired, be provided withconductive materials such as interlaid wire which, when and if broken,would actuate a security alarm. Typical of security glazing for an alarmis one prepared using a vacuum bag as above with a temperature of 275°F., a pressure of 250 psi and a hold time of 30 minutes at temperature,and having an outboard layer of 125 mils of primed glass, an interlayerof 30 mils of the above LR 3320 block copolymer, a 250 mil thick layerof polycarbonate, another interlayer of 30 mils of the above LR resinhaving interlaid thereon, as desired, an alarm wire and finally aninboard or inner layer of about 125 mils of glass.

Security glazing without the alarm feature can be provided by simplyomitting the alarm wire in the above example. Conductive layers can alsobe used. Such electrical inserts can also be used for heating.

The above security glazing complies with American National StandardsInstitute Standard ANSI Z97.1--1972, there being no fracture of theglazing surface after repeated impacts at the 400 ft-lb. energy level.

Laminates using the present block copolymers as an interlayer find usealso in applications where resistance to high speed forceful missilessuch as bullets is desirable, such laminates finding application inglazing, taxicab partitions, tellers' windows, and the like.

EXAMPLE II

There was prepared a laminate having three plies of polycarbonate withone ply of 15 mil LR 3320 block copolymer between each of the adjacentpolycarbonate sheets. When this laminate was subjected to the UL 752Standard test for resistance to bullets, there was no penetration orspalling of the inboard layer using medium power (Super 38 automatic),high power (0.357 magnum revolver), or super power (0.44 magnumrevolver) small arms ammunition and weapons. Tests were performed atroom temperature, 120° F., and one side at -25° F. according to thestandard. This laminate was prepared using a vacuum ring and atemperature of 250° F. and a pressure of 200 psi for a 30 minute holdtime.

EXAMPLE III

There was prepared a bullet resistant laminate having an outer layer of125 mils of primed strengthened glass, an interlayer of 60 mils of thementioned LR 5630 block copolymer, a layer of 250 mils of polycarbonate,an interlayer of 30 mils of the mentioned LR 3320 block copolymer, andan inboard ply of 375 mils of polycarbonate. When tested at roomtemperature according to UL Standard 752 for Bullet Resisting Glazing,it was both penetration and spall resistant to super 38 and 0.357 magnumammunition. This laminate was prepared in a vacuum bag using atemperature of 250° F. and a pressure of 250 psi and a hold time of 45minutes.

EXAMPLE IV

The present laminates are also useful for gas mask lenses, which areductile, penetration and abrasion resistant and retain their qualitiesand flexibility and clarity over a wide range of temperatures. Therewere bonded together in a platen press at 290° F. and 200 psi for 10minutes, using 60 mils of LR 4330 block copolymer, about two mils ofmar-resistant coated polycarbonate and about 1 mil of polyvinylidenechloride (SARAN). This was repeated using polyethylene terephthalatefilm (MYLAR) in place of polyvinylidene chloride as thepermeation-resistant layer. Lenses so prepared were flexible and clearover a range of from below -25° F. to 150° F. LR 4330 has a specificgravity of 1.09, a tensile strength of 2600 psi, a tear strength (Die C)of 320 pounds per inch, a brittleness temperature of less than -76° F.and a heat deflection temperature (10 mils under 66 psi load) of 190° F.

EXAMPLE V

A laminate was made using polymethyl methacrylate 1/8 inch thick and 1/8inch annealed polycarbonate with an interlayer of 15 mils of LR-3320.Prior to lamination, the polycarbonate was treated for 4 hours at 285°F. and allowed to cool overnight. The laminate was prepared in a steamheated platen press starting at 100° F. and raising the temperature to275° F. for 30 minutes at 200 psi, cooling for 5 minutes to ambientunder 200 psi pressure. To prevent sideways extrusion of the acrylicedge guides were used as a mold.

The laminate prepared as indicated was further modified to bond theacrylic surface to 1/8 inch thick potassium ion exchanged soda limeglass utilizing a cast-in-place acrylic-based interlayer system. Thecast-in-place techniques utilized were standard state of the art with anovernight room temperature cure.

The resultant laminates with or without one glass surface are useful forballistics and fragment resistance. In either case, the polycarbonatesurface should be positioned opposite the impacting projectile.

It will be realized that the above examples are typical only of thepractice of the invention. Thus, greater and lesser thicknesses of thevarious layers can be used where indicated. Likewise, while specificprocesses have been described in connection with the examples, generallyspeaking other methods of laminating can be adapted to the making of theexemplary structures. It will also be realized that the block copolymercan be used in solution form.

The present invention finds use in any of a number of applications andparticularly where high strength or impact resistance are prescribedalong with clarity and integrity. Among such uses are glazing generally,windshields, telephone and waiting booths, bank windows, lenses,lighting fixtures, vending machines, decorative glazing and the like. Aspointed out above, electric wires or conductive layers can be locatedwithin the laminates for alarm or heating purposes.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:
 1. A laminate of an acrylic polymer and other materialselected from the group comprising solid resinous material, glass, wood,ceramics, metals and cermets and having as adhesive interlayer blockpolysiloxane-polycarbonate copolymer prepared by reacting (A) a halogenchain-stopped polydiorganosiloxane composed of from about 5 to 200chemically combined diorganosiloxy units consisting essentially ofdialkylsiloxy units which are connected to each other bysilicon-oxygen-silicon linkages wherein each of the silicon atoms hastwo organo radicals attached through a carbon-silicon bond, and (B) adihydric phenol having the formula ##STR6## where Z is a member selectedfrom the class consisting of hydrogen, lower alkyl radicals and halogenradicals and combinations thereof, and R is a member selected from theclass consisting of hydrogen, hydrocarbon and halogenated hydrocarbonradicals, and phosgenating the purified reaction product until theresulting copolymer achieves a maximum intrinsic viscosity.
 2. Alaminate as in claim 1 wherein the other material is acrylic.
 3. Alaminate as in claim 1 wherein the other material is glass.
 4. Alaminate as in claim 1 wherein the other material is a solid resinousmaterial.
 5. A laminate as in claim 4 wherein the solid resinousmaterial is polycarbonate.
 6. A laminate as in claim 1 having includedtherein electrically conductive material.
 7. A laminate as in claim 3wherein the glass surface adjacent to the block copolymer are primedwith an adhesion promoting primer.
 8. A laminate as in claim 5 whereinthe exposed surface of polycarbonate has a mar-resistant coating.